indefinable
1. [ adjective ] not capable of being precisely or readily described; not easily put into words
Synonyms: undefinable
Examples:

"an indefinable feeling of terror" "an abstract concept that seems indefinable"

Related terms: undefined
2. [ adjective ] defying expression or description
Synonyms: unspeakable indescribable untellable ineffable unutterable
Examples:

"indefinable yearnings" "indescribable beauty" "ineffable ecstasy" "inexpressible anguish" "unspeakable happiness" "unutterable contempt" "a thing of untellable splendor"

Related terms: inexpressible
Similar spelling:   indefatigable
  indefeasible
  indefinite
  indefinitely
  indefensible
  indefatigably
  indefinity
  indefiniteness
  inadvisable